MILLIMETER WAVE SPECTRUM OF ISOCYANAMIDE, $H_{2}N-NC$

Author Institution:The a-type rotational spectrum of isocyanamide was observed in the frequency range 147 GHz and 300 GHz. Ether extraction of the hydrolysis products of diazomethyllithium was employed to isolate the isocyanamide. 53 rotational lines wore assigned to molecules in the ground vibrational state ($NH_{2}$-inversion state $O^{+}$) and in the lowest vibrational state ($NH_{2}$-inversion state $O^{-}$). The centrifugal distortion analysis yielded for each state three rotational constants and seven centrifugal distortion constants. The rotational constants and the asymmetry parameters are: $0^{+}$ state: $A=282152(140) MHz, B=10757.2791(22) MHz, C=10525.3389(23) MHz, b_{p}=-4.2713\cdot10^{-4}. \kappa=-0.998295. O^{-}$ state: $A=282139(130) MHz, B= 10756.7698(22) Mhz, C=10525.2509(21) Mhz, b_{p}=-4.2637\cdot10^{-4}, \kappa=-0.998295$. The comparison of these rotational constants with the existing ab-initio results confirm beyond doubt that the data reported here arise from isocyanamide. A prediction of the laboratory rest frequencies for the a-type R-branch rotational transitions in the microwave and millimeter wave range is presented for both inversion states $0^{+}$ and $0^{-}$ in order to foster the radioastronomical search for $H_{2}N-NC$